On Mon, Jun 18, 2012 at 02:53:10PM +0800, Asias He wrote:
> +static void virtblk_make_request(struct request_queue *q, struct bio *bio)
> +{
> + struct virtio_blk *vblk = q->queuedata;
> + unsigned int num, out = 0, in = 0;
> + struct virtblk_req *vbr;
> +
> + BUG_ON(bio->bi_phys_segments + 2 > vblk->sg_elems);
> + BUG_ON(bio->bi_rw & (REQ_FLUSH | REQ_FUA));
> +
> + vbr = virtblk_alloc_req(vblk, GFP_NOIO);
> + if (!vbr) {
> + bio_endio(bio, -ENOMEM);
> + return;
> + }
> +
> + vbr->bio = bio;
> + vbr->req = NULL;
> + vbr->out_hdr.type = 0;
> + vbr->out_hdr.sector = bio->bi_sector;
> + vbr->out_hdr.ioprio = bio_prio(bio);
> +
> + sg_set_buf(&vbr->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr));
> +
> + num = blk_bio_map_sg(q, bio, vbr->sg + out);
> +
> + sg_set_buf(&vbr->sg[num + out + in++], &vbr->status,
> + sizeof(vbr->status));
> +
> + if (num) {
> + if (bio->bi_rw & REQ_WRITE) {
> + vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
> + out += num;
> + } else {
> + vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
> + in += num;
> + }
> + }
> +
> + spin_lock_irq(vblk->disk->queue->queue_lock);
> + if (virtqueue_add_buf(vblk->vq, vbr->sg, out, in, vbr,
> + GFP_ATOMIC) < 0) {
> + spin_unlock_irq(vblk->disk->queue->queue_lock);
Any implications of dropping lock like that?
E.g. for suspend. like we are still discussing with
unlocked kick?
> + virtblk_add_buf_wait(vblk, vbr, out, in);
> + } else {
> + virtqueue_kick(vblk->vq);
Why special case the first call? task state manipulation so expensive?
> + spin_unlock_irq(vblk->disk->queue->queue_lock);
> + }
> +}
> +
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